单项选择题 A customer has 2 DS1s to add between adjacent nodes in a UPSR ring. What type of circuit should you recommend?（）

单项选择题 Click the Exhibit button. Given the information shown in the exhibit, when creating 2 DS1 circuits, how many STS ports are used on the VT1.5 matrix at Node 1 as VT circuits and how many are used after using VT tunnels?（）

单项选择题 A customer wants to create a 1:1 protection group with a DS3N-12 card. Which card slots would allow for a 1:1 protection?（）